Magnetic Stripe Readers (MSR) are the devices through which a credit or debit cards are swiped and read. These are by far the most common device in all segments of the retail and service world today. If you take credit cards, you have some form of MSR. If you donít have a POS system, you may have a receipt printer that has a built-in MSR.

Most MSRs are attached to the side of monitors of POS systems. Some, like in grocery stores, are stand alone units that also have pin pads (number pads) for people to punch in telephone or other numbers. There are one-stripe, two-stripe and three-stripe readers. The two-stripe reader allows a reader to get both account number and name from the card. A three-stripe reader can have customized information on the third stripe. Almost all MSRs sold today are three stripe readers.

The use of the magnetic strip is actually quite prevalent in many industries today, including the transit industry (fare cards), the security industry (door locks), the gift card market, and government (drivers license, food stamps, etc.). A good history with a detailed technical overview of the magnetic stripe, including the story of how the inventor had the help of his wife and her ironing board in coming up with the original solution, can be found here.

There are five basic interfaces for MSRs and a POS system - serial port direct, serial port emulation with USB (known as CDC), keyboard emulation with USB, keyboard "wedge", and "human interface device (HIB)" with USB. The interface you buy will depend on the configuration of your POS hardware and software. For instance, if your MSR is attached to your keyboard, you will want a wedge interface. This uses a Y type connection to connect the keyboard to the device and then the device to the 6 pin DIN keyboard connector on the computer. The USB with keyboard emulation allows both devices to be connected separately, but still treats input from the MSR as if it is coming from the computer. In almost all cases, there may be software configurations and/or driver downloads necessary to make your device work properly. This will depend on the POS software you are running.